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Protein

Heme oxygenase 1, chloroplastic

Gene

HO1

Organism
Arabidopsis thaliana (Mouse-ear cress)
Status
Reviewed-Annotation score: Annotation score: 5 out of 5-Experimental evidence at protein leveli

Functioni

Key enzyme in the synthesis of the chromophore of the phytochrome family of plant photoreceptors. Catalyzes the opening of the heme ring to form the open-chain tetrapyrrole biliverdin IX with the release of iron and carbon monoxide (CO). Produces specifically the biliverdin IX-alpha isomer. Can form complex with heme, is ferredoxin-dependent and its activity is increased in the presence of ascorbate. Plays a role in salt acclimation signaling. May affect the plastid-to-nucleus signaling pathway by perturbing tetrapyrrole synthesis. The plastid-to-nucleus signal plays an important role in the coordinated expression of both nuclear- and chloroplast-localized genes that encode photosynthesis-related proteins.12 Publications

Catalytic activityi

Protoheme + 3 [reduced NADPH--hemoprotein reductase] + 3 O2 = biliverdin + Fe2+ + CO + 3 [oxidized NADPH--hemoprotein reductase] + 3 H2O.2 Publications

Enzyme regulationi

Activated by ascorbate.1 Publication

Kineticsi

  1. KM=1.3 µM for hemin2 Publications
  2. KM=1.9 µM for ferredoxin2 Publications
  3. KM=420 µM for ascorbate2 Publications

    pH dependencei

    Optimum pH is 7.2.2 Publications

    Sites

    Feature keyPosition(s)LengthDescriptionGraphical viewFeature identifierActions
    Metal bindingi86 – 861Iron (heme axial ligand)By similarity

    GO - Molecular functioni

    • heme binding Source: TAIR
    • heme oxygenase (decyclizing) activity Source: TAIR
    • metal ion binding Source: UniProtKB-KW

    GO - Biological processi

    • carotenoid biosynthetic process Source: TAIR
    • cellular response to UV-C Source: TAIR
    • chloroplast-nucleus signaling pathway Source: TAIR
    • flavonoid biosynthetic process Source: TAIR
    • heme oxidation Source: InterPro
    • photosynthesis Source: UniProtKB-KW
    • phytochromobilin biosynthetic process Source: TAIR
    • regulation of meristem growth Source: TAIR
    • regulation of stomatal movement Source: TAIR
    Complete GO annotation...

    Keywords - Molecular functioni

    Oxidoreductase

    Keywords - Biological processi

    Photosynthesis

    Keywords - Ligandi

    Heme, Iron, Metal-binding

    Enzyme and pathway databases

    BioCyciARA:AT2G26670-MONOMER.
    MetaCyc:AT2G26670-MONOMER.

    Names & Taxonomyi

    Protein namesi
    Recommended name:
    Heme oxygenase 1, chloroplastic (EC:1.14.14.182 Publications)
    Short name:
    AtHO1
    Alternative name(s):
    Protein GENOMES UNCOUPLED 2
    Protein REVERSAL OF THE DET PHENOTYPE 4
    Gene namesi
    Name:HO1
    Synonyms:GUN2, HY1, HY6, TED4
    Ordered Locus Names:At2g26670
    ORF Names:F18A8.4
    OrganismiArabidopsis thaliana (Mouse-ear cress)
    Taxonomic identifieri3702 [NCBI]
    Taxonomic lineageiEukaryotaViridiplantaeStreptophytaEmbryophytaTracheophytaSpermatophytaMagnoliophytaeudicotyledonsGunneridaePentapetalaerosidsmalvidsBrassicalesBrassicaceaeCamelineaeArabidopsis
    Proteomesi
    • UP000006548 Componenti: Chromosome 2

    Organism-specific databases

    TAIRiAT2G26670.

    Subcellular locationi

    GO - Cellular componenti

    • chloroplast Source: TAIR
    Complete GO annotation...

    Keywords - Cellular componenti

    Chloroplast, Plastid

    Pathology & Biotechi

    Disruption phenotypei

    Long hypocotyl, incomplete chloroplast and leaf development, lack of photoreversible phytochromes and lack of phytochromobilin, the phytochrome chromophore. No cotyledon expansion in response to bright-red light. Increased levels of jasmonate (JA) and constitutive expression of JA-inducible defense genes. Increased sensitivity to salt stress and no acclimation response to salinity.11 Publications

    PTM / Processingi

    Molecule processing

    Feature keyPosition(s)LengthDescriptionGraphical viewFeature identifierActions
    Transit peptidei1 – 5454ChloroplastSequence analysisAdd
    BLAST
    Chaini55 – 282228Heme oxygenase 1, chloroplasticPRO_0000412185Add
    BLAST

    Proteomic databases

    PaxDbiO48782.
    PRIDEiO48782.

    PTM databases

    iPTMnetiO48782.

    Expressioni

    Tissue specificityi

    Widely expressed.3 Publications

    Inductioni

    By salt treatment. Down-regulated by jasmonate.2 Publications

    Gene expression databases

    GenevisibleiO48782. AT.

    Interactioni

    Protein-protein interaction databases

    BioGridi2560. 1 interaction.
    STRINGi3702.AT2G26670.1.

    Structurei

    3D structure databases

    ProteinModelPortaliO48782.
    SMRiO48782. Positions 88-277.
    ModBaseiSearch...
    MobiDBiSearch...

    Family & Domainsi

    Sequence similaritiesi

    Belongs to the heme oxygenase family.Curated

    Keywords - Domaini

    Transit peptide

    Phylogenomic databases

    eggNOGiKOG4480. Eukaryota.
    COG5398. LUCA.
    HOGENOMiHOG000265822.
    InParanoidiO48782.
    KOiK00510.
    OMAiWEPTVDG.
    OrthoDBiEOG09360KFI.
    PhylomeDBiO48782.

    Family and domain databases

    Gene3Di1.20.910.10. 1 hit.
    InterProiIPR016053. Haem_Oase-like.
    IPR016084. Haem_Oase-like_multi-hlx.
    IPR016951. Haem_Oase_decyc_pln.
    [Graphical view]
    PfamiPF01126. Heme_oxygenase. 1 hit.
    [Graphical view]
    PIRSFiPIRSF030219. Heme_Oase_decyc_pln. 1 hit.
    SUPFAMiSSF48613. SSF48613. 1 hit.

    Sequences (2)i

    Sequence statusi: Complete.

    Sequence processingi: The displayed sequence is further processed into a mature form.

    This entry describes 2 isoformsi produced by alternative splicing. AlignAdd to basket

    Isoform 1 (identifier: O48782-1) [UniParc]FASTAAdd to basket

    This isoform has been chosen as the 'canonical' sequence. All positional information in this entry refers to it. This is also the sequence that appears in the downloadable versions of the entry.

    « Hide

            10         20         30         40         50
    MAYLAPISSS LSIFKNPQLS RFQFSSSSPN PLFLRPRIQI LSMTMNKSPS
    60 70 80 90 100
    LVVVAATTAA EKQKKRYPGE SKGFVEEMRF VAMRLHTKDQ AKEGEKETKS
    110 120 130 140 150
    IEERPVAKWE PTVEGYLRFL VDSKLVYDTL ELIIQDSNFP TYAEFKNTGL
    160 170 180 190 200
    ERAEKLSTDL EWFKEQGYEI PEPTAPGKTY SQYLKELAEK DPQAFICHFY
    210 220 230 240 250
    NIYFAHSAGG RMIGRKVAER ILDNKELEFY KWDGELSQLL QNVREKLNKV
    260 270 280
    AEEWTREEKN HCLEETEKSF KYSGEILRLI LS
    Length:282
    Mass (Da):32,691
    Last modified:November 1, 1999 - v2
    Checksum:i65D9638890A3E8BA
    GO
    Isoform 2 (identifier: O48782-2) [UniParc]FASTAAdd to basket

    The sequence of this isoform differs from the canonical sequence as follows:
         94-142: GEKETKSIEERPVAKWEPTVEGYLRFLVDSKLVYDTLELIIQDSNFPTY → D

    Note: Derived from EST data. No experimental confirmation available.
    Show »
    Length:234
    Mass (Da):27,076
    Checksum:iD5350323BB620A1E
    GO

    Sequence cautioni

    The sequence AAK52998 differs from that shown. Reason: Erroneous initiation. Translation N-terminally extended.Curated

    Alternative sequence

    Feature keyPosition(s)LengthDescriptionGraphical viewFeature identifierActions
    Alternative sequencei94 – 14249GEKET…NFPTY → D in isoform 2. CuratedVSP_041652Add
    BLAST

    Sequence databases

    Select the link destinations:
    EMBLi
    GenBanki
    DDBJi
    Links Updated
    AB021857 Genomic DNA. Translation: BAA77758.1.
    AB021858 mRNA. Translation: BAA77759.1.
    AF132475 Genomic DNA. Translation: AAD22107.1.
    AF132476 Genomic DNA. Translation: AAD22108.1.
    AC003105 Genomic DNA. Translation: AAB95301.2.
    CP002685 Genomic DNA. Translation: AEC07872.1.
    CP002685 Genomic DNA. Translation: AEC07873.1.
    AF327418 mRNA. Translation: AAG42008.2.
    AF375414 mRNA. Translation: AAK52998.1. Different initiation.
    AY129477 mRNA. Translation: AAM91063.1.
    BT002327 mRNA. Translation: AAN86160.1.
    AY087288 mRNA. Translation: AAM64841.1.
    PIRiT52457.
    RefSeqiNP_001118392.1. NM_001124920.1. [O48782-2]
    NP_180235.1. NM_128224.2. [O48782-1]
    UniGeneiAt.23645.

    Genome annotation databases

    EnsemblPlantsiAT2G26670.1; AT2G26670.1; AT2G26670. [O48782-1]
    GeneIDi817208.
    KEGGiath:AT2G26670.

    Keywords - Coding sequence diversityi

    Alternative splicing

    Cross-referencesi

    Sequence databases

    Select the link destinations:
    EMBLi
    GenBanki
    DDBJi
    Links Updated
    AB021857 Genomic DNA. Translation: BAA77758.1.
    AB021858 mRNA. Translation: BAA77759.1.
    AF132475 Genomic DNA. Translation: AAD22107.1.
    AF132476 Genomic DNA. Translation: AAD22108.1.
    AC003105 Genomic DNA. Translation: AAB95301.2.
    CP002685 Genomic DNA. Translation: AEC07872.1.
    CP002685 Genomic DNA. Translation: AEC07873.1.
    AF327418 mRNA. Translation: AAG42008.2.
    AF375414 mRNA. Translation: AAK52998.1. Different initiation.
    AY129477 mRNA. Translation: AAM91063.1.
    BT002327 mRNA. Translation: AAN86160.1.
    AY087288 mRNA. Translation: AAM64841.1.
    PIRiT52457.
    RefSeqiNP_001118392.1. NM_001124920.1. [O48782-2]
    NP_180235.1. NM_128224.2. [O48782-1]
    UniGeneiAt.23645.

    3D structure databases

    ProteinModelPortaliO48782.
    SMRiO48782. Positions 88-277.
    ModBaseiSearch...
    MobiDBiSearch...

    Protein-protein interaction databases

    BioGridi2560. 1 interaction.
    STRINGi3702.AT2G26670.1.

    PTM databases

    iPTMnetiO48782.

    Proteomic databases

    PaxDbiO48782.
    PRIDEiO48782.

    Protocols and materials databases

    Structural Biology KnowledgebaseSearch...

    Genome annotation databases

    EnsemblPlantsiAT2G26670.1; AT2G26670.1; AT2G26670. [O48782-1]
    GeneIDi817208.
    KEGGiath:AT2G26670.

    Organism-specific databases

    TAIRiAT2G26670.

    Phylogenomic databases

    eggNOGiKOG4480. Eukaryota.
    COG5398. LUCA.
    HOGENOMiHOG000265822.
    InParanoidiO48782.
    KOiK00510.
    OMAiWEPTVDG.
    OrthoDBiEOG09360KFI.
    PhylomeDBiO48782.

    Enzyme and pathway databases

    BioCyciARA:AT2G26670-MONOMER.
    MetaCyc:AT2G26670-MONOMER.

    Miscellaneous databases

    PROiO48782.

    Gene expression databases

    GenevisibleiO48782. AT.

    Family and domain databases

    Gene3Di1.20.910.10. 1 hit.
    InterProiIPR016053. Haem_Oase-like.
    IPR016084. Haem_Oase-like_multi-hlx.
    IPR016951. Haem_Oase_decyc_pln.
    [Graphical view]
    PfamiPF01126. Heme_oxygenase. 1 hit.
    [Graphical view]
    PIRSFiPIRSF030219. Heme_Oase_decyc_pln. 1 hit.
    SUPFAMiSSF48613. SSF48613. 1 hit.
    ProtoNetiSearch...

    Entry informationi

    Entry nameiHMOX1_ARATH
    AccessioniPrimary (citable) accession number: O48782
    Secondary accession number(s): B3H4A6, Q7E9A5, Q9FPE3
    Entry historyi
    Integrated into UniProtKB/Swiss-Prot: July 27, 2011
    Last sequence update: November 1, 1999
    Last modified: September 7, 2016
    This is version 104 of the entry and version 2 of the sequence. [Complete history]
    Entry statusiReviewed (UniProtKB/Swiss-Prot)
    Annotation programPlant Protein Annotation Program

    Miscellaneousi

    Keywords - Technical termi

    Complete proteome, Reference proteome

    Documents

    1. Arabidopsis thaliana
      Arabidopsis thaliana: entries and gene names
    2. SIMILARITY comments
      Index of protein domains and families

    Similar proteinsi

    Links to similar proteins from the UniProt Reference Clusters (UniRef) at 100%, 90% and 50% sequence identity:
    100%UniRef100 combines identical sequences and sub-fragments with 11 or more residues from any organism into one UniRef entry.
    90%UniRef90 is built by clustering UniRef100 sequences that have at least 90% sequence identity to, and 80% overlap with, the longest sequence (a.k.a seed sequence).
    50%UniRef50 is built by clustering UniRef90 seed sequences that have at least 50% sequence identity to, and 80% overlap with, the longest sequence in the cluster.